Metla Project 3477

The effects of stemwood and wholetree harvesting in drained peatlands on leaching of nutrients and heavy metals to water courses and nutrient sufficiency for sustainable treeproduction

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Duration: 2007-2012   Keywords: Bioenergy, Element budgets, Leaching, Loggin residues, Nutrien capitals, Stump lifting, Whole-tree harvesting
Research project group: Distinct projects 1 - Structure and function of forest ecosystems

Objectives

In Finland 4.95 million ha of peatlands have been drained for forestry, and much of it will be at the final stage of the rotation period and harvested within 10 to 30 years. In Finland it is planned to increase the amount of tree biomass for use in bioenergy production to 7.5 milj m-3 by 2015. To achieve this target, logging residues (tree tops, branches and stumps) will have to be used in addition to stemwood. There are no previous investigations on drained peatlands about the effects of whole-tree harvesting on postharvest hydrological losses, site nutrient capital, nutrient and heavy metal leaching, or regrowth.

The aim of the present research project is to study those by comparing the traditional stem-only cutting with whole-tree harvesting. Subproject 347701 concentrates especially on nutrient leaching and supply questions and subproject 347702 nutrient- and heavy metal leaching including effects of local bedrock.

Subprojects

Subproject 347701: Stem-only cutting and whole-tree harvesting on peatlands drained for forestry: Effects on nutrient sufficiency for sustainable tree production and leaching losses to water courses

There are no previous investigations on peatlands drained for forestry about the effects of whole-tree harvesting on postharvest hydrological losses, site nutrient capital, or regrowth.

The aim of the present research project is to study those by comparing the traditional stem-only cutting with whole-tree harvesting, and the effects of stump-lifting are also studied from the viewpoint of site nutrient capital and nutrient leaching to recipient water courses.

Keywords: Drained peatlands, whole-tree harvesting, stump lifting, nutrient capitals, hydroligical nutrient losses.
Project leader: Mika Nieminen (VA)
Other researchers: Timo Penttilä (VA), Jyrki Hytönen (KA), Mikko Moilanen (MU)

Subproject 347702: Stem only vs. whole-tree harvesting - the effects of harvesting in forested peatlands on the leaching of nutrients and heavy metals

According to current energy policy logging residues (tree tops, branches and stumps) will have to be used in addition to stemwood. Most of the researches into stem-only and whole-tree harvesting have been carried out on upland sites, and little is known about drained peatland forests. This would provide a major source of bioenergy. It is therefore important to evaluate not only the potential of whole-tree harvesting of drained peatland forests in terms of bioenergy source, but also its ecological effects. It is hypothesized that whole-tree harvesting might reduce nutrients leaching to waters. However the disturbance of the forest floor might increase leaching of nutrients and heavy metals. In addition higher water table level due to harvesting effects on runoff water quality, especially in peatlands underlain by black-shale (known to be rich in easily weathering heavy metals) compared areas underlain by granitic bedrock. In addition, anoxic conditions can develop in pools of standing water formed as results of harvesting, especially after stump removing, and result in mobilization of heavy metals that have accumulated in the soils and subsequent transport to surface waters, where they pose an eco-toxicological risk.

Our aim is to compare the effects of stem only and whole-tree harvesting, including stump removal, on the release and transport of 1) major nutrients and growth limiting trace elements such as boron and 2) heavy metals (Hg, Pb, Cd) to surface waters. We will further investigate 3) differences in nutrient and heavy metal losses between catchments on different bedrock types (black shale granitic bedrock).

Keywords: Bioenergy, black shale, drained peatlands, element budgets, final felling, heavy metals, leaching, load, logging residues, steamwood harvesting, stumps, whole-tree harvesting.
Project leader: Liisa Ukonmaanaho
Other researchers: Tiina Nieminen (VA), Erkki Ahti (VA), Mika Nieminen (VA), Marjatta Kantola (VA), Juha Piispanen (MU)

Project leader: Ukonmaanaho, Liisa
The Finnish Forest Research Institute, Vantaa Unit, PO Box 18 (Jokiniemenkuja 1), FI-01301 VANTAA, FINLAND
Phone: +358 29 532 5115
E-mail: liisa.ukonmaanaho@metla.fi

Other researchers: Fritze, Hannu, VA (2012), Hartman, Markus, VA (2011), Hytönen, Jyrki, KA (2008-12), Hökkä, Hannu, RO (2012), Koskela, Merja-Leena, VA (2008-12), Lauren, Ari, JO (2010), Merilä, Päivi, OU (2010), Moilanen, Mikko, OU (2012), Nieminen, Mika, VA (2008-12), Nieminen, Tiina, VA (2008-12), Nousiainen, Hannu, VA (2008), Ruokolainen, Maija, VA (2008-12)


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Updated 02.02.2013
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